By virtue of the high efficiency and the power-saving performance, LED illumination exhibits economic benefits, such as notable consumption reduction, energy saving, etc., and therefore has been vigorously promoted and widely applied in many illumination fields and other industries in recent years. At the current level of industrial technology, the technique of LED monochromatic chip added with phosphor is still the dominant fashion to achieve a white-light LED. The most common encapsulation form is excitation chips coated with fluorescent powder gel. The poor thermally conducting performance of fluorescent gel, and the directly contacting with the excitation chips that emitting light and heat, easily lead to thermal aging of the coated fluorescent powder gel, which affects the light quality and operation stability of the white light source.
In terms of illumination popularization and application, the white-light LED still has an essential drawback of low luminous flux. As an illuminating light source, it must emit more light and achieve a higher utilization efficiency of energy. Obviously, the power of a single chip is unable to meet the requirements of the illumination field on high brightness and high power. Since large-power LED modules are developed with the tendency of high integration and volume miniaturization, it is necessary to look for the technology for large-power and highly integrated white-light LED, in order to achieve the luminous flux required for general illumination.